1. Field of the Invention
The present application relates generally to a bonding strength test device which measures bonding strength of an electronic component such as a microactuator mounted on the flexure of a hard disk drive, and a method for measuring bonding strength using the same device.
2. Description of the Related Art
To meet increasing recording density of hard disk drives, a microactuator including a piezoelectric device is often mounted on the suspension of the drive. The microactuator is an example of an electronic component.
As disclosed in JP 2012-94237 A (Patent Literature 1), a gimbal assembly in which a microactuator is mounted on a flexure at the tip of a suspension is known. In that case, such a microactuator must be miniaturized as compared to a case where a microactuator is mounted on the base plate of the suspension.
The contact surface of the microactuator and the flexure is reduced by the miniaturization, and the bonding strength therebetween becomes a quality control issue. As an evaluation method of bonding strength, a shear test is well-known as disclosed in JP 2002-22650 A (Patent Literature 2).
However, the bonding strength measured in a shear test is limited to sway directions. In addition to track width directions of the magnetic disk (sway directions), the flexure moves vertically in both the direction approaching the magnetic disk (loading direction) and the direction departing from the magnetic disk (unloading direction). Thus, impact of acceleration/deceleration is applied in the loading/unloading direction.
To improve the reliability of hard disk drives, a test method used for measuring bonding strength of microactuators in loading and unloading directions is demanded. There are, for example, proposed methods disclosed by JP 1996-111417 A (Patent Literature 3), JP 1999-288986 A (Patent Literature 4), and JP 2009-180620 A (Patent Literature 5) as means for measuring bonding strength of electronic components mounted on a substrate in their thickness direction.
However, with means disclosed by Patent Literatures 3 to 5, fixing of small and fragile microactuators to a test device is difficult to achieve.
Since a piezoelectric device which is a ceramic component of the microactuator lacks thermoplasticity, a fixing method by seizing disclosed in Patent Literature 3 cannot be adopted. Such a method is inappropriate for an additional reason that preparation for the test becomes complicated. Furthermore, since a piezoelectric device is weak, a fixing method by chucking disclosed in Patent Literature 4 is difficult to adopt. Furthermore, since a microactuator is small enough to be mounted on a flexure, a vacuum fixing method disclosed in Patent Literature 5 is difficult to adopt.